Cross flow machine



May 30, 1967 N. LAING 3,322,333

CROS S FLOW MACHINE Original Filed Sept, 5, 1962 I5 Sheets-Sheet l INVENTOR Nikoc aus Luing BY W M an; 5 00% ATTORNEYS May 30, 1967 N. LAING 3,322,333

CROSS FLOW MACHINE Original Filed Sept. 5, 1962 s sheets sheet 2 INVENTOR Nikolaus Loing BY e ,..p M 19m;

ATTORNEYS May 30, 1967 N. LAING CROSS FLOW MACHINE 3 Sheets-Sheet 6 Original Filed Sept. 5. 1962 INVENTOR 'Nilfzlous Loing Y a g 1 ATTORNEYS United States Patent 3,322,333 CROSS FLOW MACHINE Nikolaus Laing, Stuttgart, Germany, assignor, by mesne assignments, to Laing Vortex, Inc., New York, N.Y. Original application Sept. 5, I962, Ser. No. 221,621, now

Patent No. 3,232,522. Divided and this application Jan.

3, 1966, Ser. No. 518,259

Claims riority, application Germany, Dec. 7, 1956,

E 13,333, L 26,389 7 Claims. (Cl. 230-125) This invention relates to machines for inducing movement of fluid, which is understood as including 'both liquids and gases; this application is a division of copending application Ser. No. 221,621 filed Sept. 5, 1962, now Patent No. 3,232,522, itself a continuation-in-part of application Ser. No. 671,114 filed July 5, 1957, now abandoned. The invention more particularly concerns flow machines of the cross-flow type, that is, machines comprising a cylindrical bladed rotor mounted for rotation about its axis in a predetermined direction and defining an interior space, and guide means defining With the rotor an entry region and a discharge region, the guide means and rotor co-operating ion rotation of the latter in said predetermined direction to induce a flow of fluid from the entry region through the path of the rotating blades of the rotor to said intenior space andthence again through the path of said rotating blades to the discharge region. More especially but not exclusively, the invention concerns fans of the cross-flow type wherein the guide means and rotor co-ope-rate to set up a vortex of Rankine character having a core region eccentric of the rotor axis and a field region which guides the fluid so that flow through the rotor is strongly curved about the vortex core: such flow machines will herein be designated tangential machines and the characteristics of a preferred form of such a machine will be described in detail later.

I have found that the tangential flow machine as above defined is Well adapted to produce a fluid flow which due to the vortex action is surprisingly fast relative to the speed of rotation of the rotor: the speed of flow may be two or more times the peripheral speed of the rotor. In many applications of the machine it will be desired to convert at least a portion of this velocity energy to pressure energy.

The norm-a1 means for converting velocity to pressure energy is a diffuser, that is a duct which gradually increases in cross-sections, going in the direction of flow. Diffusers are Well known to have two defects. First, if the duct diverges too rapidly, flow will tend to break away from the walls, forming regions of random eddying which waste energy. Second, if, to counter the first defeet the angle of divergence is reduced then energy is wasted in friction along the over-long walls. Normally a diffuser is designed as a compromise to minimize these opposite defects.

I have found that the flow leaving the rotor in a tangential flow machine does not have the velocity profile normally found in fluid flow machines, but is instead marked by a pronounced peak. This is due once again to the action of the vortex, by reason of which the flow in the field region is much faster adjacent the periphery of the core region than it is at a distance therefrom. The peaky velocity profile tends to cause severe energy losses due to the mixing of flow at different velocities, when the flow leaving the rotor of a tangential machine is led into a conventional diffuser. The more efficient the tangential fan the greater are these energy losses, since the efficiency of the machine is dependent on the intensity of the vortex and the more intense the vortex the greater the peak in the velocity profile, as will be apparent from the drawings discussed later.

The invention in its broad aspect resides in forming the discharge region as a diffuser having a centre line which is continuously curved in the same sense as the flow through the rotor so that the curve of flow through the rotor continues through the diffuser. Preferably the guide means comprise a guide body presenting a portion to the rotor which substends a small are at the axis thereof and a guide wall opposite the guide body, both guide body and guide wall having continuously curved surfaces defining the discharge region, the curve of the guide body being tighter than that of the guide wall. The vortex core region then forms adjacent the guide body. The fastest stream tubes detach themselves from the periphery of the core region on leaving the rotor blades for the second time and flow into the diffuser adacent the strongly curved guide body surface. Because of their high velocity, these stream tubes will tend to follow the guide body surface. The low velocity flow from the rotor will be guided by the guide Wall.

The fast stream tubes will, as it were see a strongly divergent diffuser wall which, however, they can follow because of their velocity, their velocity being thereby converted to pressure energy. The slow stream tubes do not, as it were, see a diffuser at all. In this Way the curved diffuser exploits the peculiar characteristics of the tangential fan velocity profile to enable a conversion of velocity to pressure energy in that part of the flow which has a high velocity energy. I have found that by the means described I can get good conversion efliciencies, and use diffusers of what according to the prevailing concepts in the art would be regarded as very wide angles.

In one preferred embodiment of the invention, at least one intermediate wall extends lengthwise of the rotor within the discharge region to divide it into two or more diffusing channels, each having a centre line which is continuously curved in the same sense as said flow through the rotor, This enables an increase in the overall angle of the diffuser. It also enables the divergence of the channels over their length to be such that the degree of conversion of velocity to pressure energy in each channel is inversely proportional to the average velocity at entry to that channel, so as at least approximately to equalize pressure at the outlet and thereby prevent recirculation. However, I have found that this is to some extent inherent in the curved diffusers according to the invention even if undivided.

The curved diffuser according to the present invention may be utilized in the construction of a compact multistage machine wherein each stage is a tangential rnachine as above defined. A preferred form of such machine comprises a housing having an inlet at one end and an outlet at the other and a rotor assembly mounted within the housing for rotation about the axis and made up of a number of constituent rotors. Wall means divide the housing into a number of compartments, one for each rotor. Each rotor cooperates with guide mean to provide an elementary tangential machine, or stage. The rotor nearest the inlet receives air therefrom and discharges it to the next rotor, and so on until the last rotor of the assembly discharges to the outlet. Guide means define between each pair of adjacent rotors a curved diffuser leading from the discharge region of one to the entry region of the next. This arrangement eflectively utilizes, as a means to increase pressure, the duct which would in any case be necessary for the conveyance of fluid between stages.

Various embodiments of the invention will now be described by way of example with reference to the accompanying somewhat diagrammatic drawings, in which:

FIGURE 1 is a cross-sectional view of a fluid flow machine constructed according to the invention and incorporating a curved diffuser;

FIGURE 2 is a graph illustrating velocity of fluid flow at the oulet of the machine of FIGURE 1;

FIGURE 3 is a graph illustrating velocity of fluid flow at the outlet of conventional machines;

FIGURE 4 is a graph illustrating velocity of fluid flow within the field of a Rankine type fluid vortex;

FIGURE 5 illustrates the ideal fluid flow lines occurring in one half the cross-sectional area of a rotor of a machine of the type shown in FIGURE 1;

FIGURE 6 is a vector diagram illustrating flow of fluid contacting a blade on its second transversal of the path of the rotating blades or when the fluid passes from the interior of the rotor to the pressure side of the machine;

FIGURE 7 is a cross-sectional view of another form of flow machine according to the invention; and

FIGURES 8 and 9 are respectively a cross-sectional view and a side elevation of a three-stage flow machine, the cross-section being taken on the line VIIIVIII in FIGURE 9.

In the various figures of drawings, similar parts will be designated by the same reference numeral and will not require further description.

Reference is made to FIGURE 1 which illustrates a flow machine having a cylindrically bladed rotor 1 which is mounted, by means not shown and without the aid of a central shaft, for rotation about its axis in the direction of the arrow 2. The rotor 1 has thereon blades 3 extending longitudinally thereof and having inner and outer edges 4 and 5 lying on inner and outer blade envelopes 6 and 7 formed when the rotor is rotated. The blades 3 are concave facing the direction of rotation and have their outer edges leading their inner edges.

A guide wall means 8 extends the length of the rotor and merges with a wall 10 to form one side of an exit duct of the machine. A guide body 9 also extends the length of the rotor and has thereon a curved wall 11 extending away from the rotor and forming part of an exit duct 19. End walls 20, only one of which is shown, cover the ends of the machine and may, although not necessarily, close the ends of the rotor. The wall 8 and guide body 9 define entry and exit arcs 12 and 13 for flow of fluid to and from the rotor. Thus the wall 8 and the body 9 provide an are for entry of fluid into the rotor which in this embodiment is substantially greater than 180 though this is by no means essential.

The guide body 9 divides the entry region S from the discharge region P. That part of the body 9 which has the greatest influence on flow through the rotor is the wall portion 9a preferably lying spaced from the rotor 6 by at least one half the blade depth rather than closely adjacent to the rotor as considered necessary in previously proposed cross-flow machines where a casing surrounds a portion of a rotor to separate pressure and suction sides of the machine. The wall portion 9a is gently curved convexly to the rotor and extends over an are substantially less than 20. It is seen that the guide body 9 presents two guide surfaces 9a and 11, which merge in an arc.

The wall 8 terminates at the zone 14 thereof where it lies nearest the rotor: at this zone the wall is spaced from the rotor a minimum of one-half the blade depth and not more than three times the blade depth.

At all events the spacing of Wall portion 9a and guide wall 8 from the rotor, in the case of a small machine working under the Reynolds number conditions, must exceed a mere working clearance and should be at least 5% of the rotor diameter; a preferred spacing in this case is 10% of the diameter. This appreciable spacing minimizes undesirable noise when the machine is operated, while at the same time, within limits, improving throughput and efliciency.

The entry are 12 and the exit arc 13 both terminate at the zone 14. From the zone 14, the wall 8 diverges steadily from the rotor in the direction of rotation indicated by arrow 2, with increasing radius of curvature: remote from rotor the wall may be straight. The wall 8 is, at all points along the exit duct 19, less tightly curved than wall 11 of the guide body. Both walls are curved in the same sense, being the sense of the curvature of the exit arc of the rotor; the curvature may be regarded as directed towards the entry region 5. Accordingly the discharge region P or exit duct 19 has the form of a diffuser with a centre or median line 19' which is continuously curved in the sense just mentioned. Intermediate or partition walls 30, 31, extending lengthwise of the rotor within the duct 19 divide it into three divergent channels 32, 33, 34 each having the character of a diffuser.

Because both the wall 8 and guide body 9 separating the pressure and suction sides of the machine are substantially spaced from the rotor, the machine c-an'be made without adhering to close manufacturing tolerances, while still eltectively separating the pressure and suction sides and maintaining the relatively high efliciency of the machine.

In operation of the FIGURE 1 machine, a vortex, having a core whose periphery is designated by the stream line V, and approximating a Rankine type vortex, is produced wherein the core is positioned eccentrically to the rotor axis. The whole throughput of the machine flows twice through the blade envelope in a direction perpendicular to the rotor axis as indicated by the stream line F, MF.

FIGURE 4 illustrates an ideal relation of the vortex to the rotor 2 and the distribution of flow velocity in the vortex and in the field of the vortex. The line 40 represents a part of the inner envelope 6 of the rotor blades 3 projected onto a straight line while the line 41 represents a radius of the rotor taken through the axis of the vortex core V. Velocity of fluid at points on the line 41 by reason of the vortex is indicated by the horizontal lines 43a, 43b, 43c and 43d, the length of these lines being the measure of the velocity at the points 43a 43b 430 and 43d The envelope of these lines is shown by the curve 44 which has two portions, portion 44a being approximately a rectangular hyperbola and the other portion, 44b, being a straight line. Line 44a relates to the field region of the vortex and the curve 44b to the core. It will be understood that the curve shown in FIGURE 4 represents the velocity of fluid where an ideal or mathematical vortex is formed, and that in actual practice, flow conditions will only approximate these curves.

The core of the vortex is a whirling mass of fluid with no translational movement as a whole and the velocity diminishes from the periphery of the core to the axis 42. The core of the vortex intersects the blade envelope as indicated at 40 and an isotach I within the vortex having the same velocity as the inner envelope contacts the envelope. The vortex core V is a region of low pressure and the location of the core in a machine constructed according to the invention can be determined by measurement of the pressure distribution Within the rotor.

The velocity profile of the fluid where it leaves the rotor and passes through the path of the rotating blades will be that of the vortex. In the ideal case of FIGURE 4, this profile will be that of the Rankine vortex there shown by curves 43a and 43b, and in actual practice, the profile will still be substantially that shown in FIG- URE 4 so that there will be in the region of the periphery of the core V shown in FIGURE 1 a flow tube MP of high velocity and the velocity profile taken at the exit of the rotor will be similar to that shown in FIGURE 2 where the line FG represents the exit of the rotor and the ordinates represent velocity. The curve shown exhibits a pronounced maximum point C which is much higher than the average velocity represented by the dotted line.

It will be appreciated that much the greater amount of fluid flows in the flow tubes in the region of maximum velocity. It has been found that approximately 80% of the flow is concentrated in the portion of the output represented by the line AE which is less than 30% of the total exit of the rotor. A conventional velocity profile for fluid flow in a defined passage is illustrated by way of contrast in FIGURE 3 where the average velocity of flow is represented by the dotted line. Those skilled in the art regard this profile as being approximately a rectangular profile which following the principle generally adhered to is the sort of profile heretofore sought in the outlet of a flow machine.

The maximum velocity C shown in FIGURE 2 appertains to the maximum velocity flow tube indicated as MP in FIGURE 1. With a given construction the physical location of the flow tube MF may be closely defined. The relative velocity between the blades and fluid in the restricted zone of the rotor blade 3 through which the flow tube MF passes is much higher than it would be if a flow machine Were designed following the conditions adhered to heretofore in the art respecting the desirability of a rectangular velocity profile at the exit arc and even loading of the blades.

Under low Reynolds number conditions, this unevenness of the velocity profile leads to beneficial results in that there will be less separation and energy loss in the restricted zone through which the flow tube MF passes than if that flow tube had the average velocity of throughput taken over the whole exit of the rotor. There is a more efficient transfer of momentum to the fluid by the blades in this restricted zone and while the transfer of momentum in the flow tubes traveling below the average velocity will be less efficient, nevertheless when all of the flow tubes are considered, there is a substantial gain in efiiciency.

FIGURE 5 illustrates the ideal distribution of flow tubes F occurring within one half the rotor area defined by the inner envelope 6, it being understood that the flow tubes in the other half of the rotor are similar. The maximum velocity flow tube MP is shown intersecting the envelope 6 at point 50 and the isotach I as being circular when the whole rotor is considered. It is seen that ideally the maximum velocity flow tube MP undergoes a change of direction of substantially 180 from the suction to the pressure sides when the flow in the whole rotor is considered. It is also to be noted that the major part of throughput, represented by the flow tube MF, passes through the rotor blades Where they have a component of velocity in a direction opposite to the main direction of flow within the rotor indicated by the arrow A.

FIGURE 6 is a diagram showing the relative velocities of flow with respect to a blade at the point 50 referred to in FIGURE 5. In this figure V represents the velocity of the inner edge of the blade 3 at the point 50, V the absolute velocity of the air in the flow tube MF at the point 50, and V the velocity of that air relative to the blade as determined by completing the triangle. The direction of the vector V coincides with that of the blade at its inner edge so that fluid flows by the blade substantially without shock.

The character of a vortex is considered as being determined largely by the blade angles and curvatures. The position of the vortex, on the other hand, is considered as be ing largely determined by the configuration of the vortex forming means which forms and stabilizes a vortex in cooperation with the bladed rotor. The particular angles and curvatures in any given case depend upon the following parameters: the diameter of the rotor, the depth of a blade in a radial direction, the density and viscosity of the fluid, the disposition of the vortex forming means and the rotational speed of the rotor, as well as the ratio between over-all pressure and back pressure. These parameters must be adapted to correspond to the :operatingconditions in a given situation. Whether or not the angle and shape of the blades have been fixed at optimum values is to be judged by the criterion that the flow tubes close to 6 the vortex core are to be deflected substantially greater than It is to be appreciated that the flow lines of FIGURE 1 do not correspond exactly to the position of the vortex core V as illustrated in FIGURES 4 and 5 which represent the theoretical or mathematical flow. These latter figures show that it is desirable to have the axis of the core of the vortex within the inner blade envelope 6 so that the isotach within the core osculates that envelope. Although this position is achieved in certain constructions hereinafter described, it is not essential, and in fact, is not achieved in the structure shown in FIGURE 1.

It is to be further appreciated that despite the divergence of the flow in FIGURE 1 from the ideal, the maximum velocity flow tube MF with which is associated the major part of the throughput is nevertheless turned through an angle of substantially in passing from the suction to the pressure side of the rotor and that this maximum flow tube passes through the rotor blades where the blades have a velocity with a component opposite to the main direction of flow through the rotor as indicated by the arrow A.

Reverting to FIGURE 1, it will be seen that the vortex core region V acts as a seal to prevent return flow of air from the discharge region vP back to the entry region S in the gap between the portion 9a of the guide body 9 and the rotor 1. According to the prior art conceptions referred to earlier herein it was attempted to prevent return flow by a wall close to the rotor over a considerable arc thereof, approximating to a mechanical seal. In the arrangement shown in FIGURE 1, the vortex core region V provides, as it were, an aerodynamic seal.

The flow tubes of maximum velocity, represented by schematically the line MF detach themselves from the periphery of the core region and flow smoothl against the curved wall 11 of the body 9. Because of their considerable velocity these flow tubes readily follow the curved wall. The slowest flow tubes emerge from the rotor 1 adjacent the wall 8 and flow along it as seen as it were, by the flow, the wall 8 does not diverge and there is therefore no tendency for the flow to break away from it. The flow tubes continue, in the exit duct 19, the curved path which they adopt in passing through the rotor. The fastest flow is received in the diffusing channel '32, the slowest in channel 34 and the flow of intermediate speed in the channel 33. The channels are designed so that the degree of conversion in a channel from velocity to pressure energy is inversely proportional to the average velocity at entry to the channel, so as at least approximately to equalize pressure at the outlet and thereby prevent recirculation.

FIGURE 7 illustrates a modified form of the flow machine of FIGURE 1, wherein the intermediate walls in the diffuser are omitted and the guide body, here designated 9', has a form differing from that above described. The guide body here shown presents a main portion 70 to the rotor defining therewith a gap 71 which tapers in the direction of rotor rotation. At its line of nearest approach to the rotor the main guide portion 70 merges into an inlet guide portion 72. Remote from the rotor the main portion 70 of the guide body 9' merges in a rounded nose '73 with an outlet guide portion 74 similar to the wall portion 11 of FIGURE 1. The exit duct 19 in this embodiment is not sub-divided. Otherwise this embodiment operates in the same manner as that of FIGURE 1.

The multi-stage machine illustrated in FIGURES 8 and 9 comprises three stages designated generally 200a, 20011 and 200e, each having cylindrically bladed rotors 201a, 1201b and 2010 mounted coaxially about a shaft 202 as a single rigid assembly contained within a generally cylindrical housing 203: the axis of the rotor assembly is parallel to, but eccentric of, that of the housing. The housing provides at one end an inlet 204 leading to the first stage 200a while the third stage 2000 discharges through an outlet 205 at the other end of the housing.

Referring to FIGURE 8, where the upper half is a part section through the rotor 201b and the lower half a part section through the rotor 201a, each rotor 201a, 201b, 201c cooperates with guide means consisting principally of a guide body 210 defining with the rotor a converging gap 211, and the interior surface 212 of the housing 203 itself. The guide means define for each rotor an entry region 213 and a discharge region 214, and cooperate with the rotor on rotation thereof to set up a vortex, as described with reference to FIGURES l to 6, the vortex core region, designated V as before, stabilizing adjacent the guide body 210 and extending into the gap 211. Flow takes place through each rotor as above described and as shown by the flow lines designated MF, F which have the same significance as in FIGURE 1. The discharge region 214, as defined between the tightly curved surface 215 of the guide body 210 and the more gently curved interior surface 212 of the housing 203, has the form of a diffuser with a centre line which is continuously curved in the same sense as the curve of flow through the rotor.

With the aid of guide walls 216 extending at a slope between the transverse partitions 206, the discharge region 214 for the rotor 201a is made to lead flow to the axially displaced entry region 213 of the rotor 2111b. As explained with reference to FIGURE 1, the faster flow represented by the line MF tends to follow the strongly curved surface 215, and some of the velocity energy possessed by the fluid on leaving the rotor 201a is converted into pressure energy. Optionally, guide vanes 217 are provided at the entry region 213 of the rotor 2011). Flow is guided in similar manner between the rotor 20112 and the entry region of the rotor 2010 and once again some velocity energy is converted to static pressure.

Flow has of course to be guided in a curved path between the stages of the machine. In the arrangement shown the ducts which would in any case be necessary take the form of curved diffusers which efficiently convert to static pressure some of the velocity energy with its peculiarly peaked profile while simultaneously providing the required guidance for flow, thus minimizing ducting losses.

The entry region for the rotor 201a communicates directly with the inlet 204, while the rotor 201a discharges directly through the outlet 205.

I claim:

1. A multi-stage flow machine comprising a housing defining an inlet adjacent one end and an outlet adjacent the other, a rotor assembly mounted within said housing for rotation about an axis and comprising a plurality of constituent rotors, one for each stage and each having longitudinally disposed blades arranged in a ring about the axis to define an interior space, wall means dividing the housing into a plurality of compartments one for each constituent rotor, guide means defining with the rotor in each compartment an entry and a discharge region, the guide means in each compartment co-operating with the rotor therein on rotation of the latter in said predetermined direction to set up a vortex of Rankine charatcer having a core region eccentric of the rotor axis and adjacent the guide body and a field region wherein fluid is guided from the entry region through the path of the rotating blades of the rotor to the interior space within the rotor and thence again through the path of the rotating blades of the rotor to the discharge region flow taking place through the rotor in planes transverse to the rotor axis and as seen in such planes being strongly curved about the vortex core, said guide means also defining a diffuser between each pair of adjacent compartments said diffuser having a centre line which is continuously curved in the same sense as flow through the rotor and leading flow from the rotor nearer the inlet to the entry region of the rotor nearer the outlet the rotor nearest the inlet having its entry region communicating therewith and the rotor nearest the outlet discharging therethrough.

2. A multi-stage flow machine as claimed in claim 1, wherein the guide means include a guide body in each compartment subtending a small angle at the rotor axis and the interior surface of the housing.

3. A multi-stage flow machine as claimed in claim 2, wherein the housing is generally cylindrical with the rotor axis eccentric of the axis of the housing.

4. A flow machine comprising a plurality of stages wherein each stage comprises a cylindrical bladed rotor mounted for rotation about its axis in a predetermined direction and defining an interior space, guide means extending the length of the rotor and defining therewith an entry region and a discharge region, the guide means comprising a guide body between said discharge and entry regions going in said predetermined direction and a guide wall opposite the guide body and defining therewith said discharge region, the guide means and rotor cooperating on rotation of the latter in said predetermined direction to set up a vortex of Rankine character having a core region eccentric of the rotor axis and adjacent the guide body and a field region wherein fluid is guided from the entry region through the path of the rotating blades of the rotor to the interior space within the rotor and thence again through the path of the rotating blades of the rotor to the discharge region, flow takin g place through the rotor in planes transverse to the rotor axis and as seen in such planes being strongly curved about the vortex core, said discharge region having the form of a diffuser with a center line which is continuously curved in the same sense as said flow through the rotor; the rotors of each stage being aligned on an axis with the discharge region of each stage except the last stage leading to the entry region of the next stage.

5. A flow machine comprising a cylindrical bladed rotor mounted for rotation about its axis in a predetermined direction and defining an interior space, guide means extending the length of the rotor and defining therewith an entry region and a discharge region, the guide means comprising a guide body between discharge and entry regions going in said predetermined direction and a guide wall opposite the guide body and defining therewith said discharge region, the guide means and rotor cooperating on rotation of the latter in said predetermined direction to set up a vortex of Rankine character having a core region eccentric of the rotor axis and adjacent the guide body and a field region wherein fluid is guided from the entry region through the path of the rotating blades of the rotor to the interior space within the rotor and thence again through the path of the rotating blades of the rotor to the discharge region with flow taking place through the rotor in planes transverse to the rotor axis and as seen in such planes being strongly curved about the vortex core, said guide wall and the portion of said guide body defining in part said discharge region each merging into a side wall curved in said predetermined direction to form a diffuser having a center line curved in said predetermined direction and wherein the curved side wall merg ing with said guide body has a greater degree of curvature than said curved side wall merging with said guide wall whereby pressure and velocity of fluid over the cross sectional area of the outlet of the diffuser are made substantially uniform.

6. A flow machine according to claim 5 having in addition at least one curved intermediate dividing wall in said diffuser having a length equal to the length of the diffuser and a width extending over the length of the rotor to form diffusing channels on either side thereof with said curved intermediate dividing wall having a greater degree of curvature than said side wall merging with said guide wall and a lesser degree of curvature than said guide wall merging with said guide body.

7. A flow machine comprising a cylindrical bladed rotor mounted for rotation about its axis in a predetermined direction and defining an interior space, guide means extending the length of the rotor and defining therewith an entry region and a discharge region, the guide means comprising a guide body between discharge and entry regions going in said predetermined direction and a guide wall opposite the guide body and defining therewith said discharge region, the guide body presenting a portion to the rotor which subtends a small are at the rotor axis and which is substantially spaced from the rotor to form a gap between said guide body portion and the rotor and presenting a portion opposite said guide wall to form said discharge region, the guide wall being spaced substantially from the rotor at its nearest approach thereto to form a gap between the guide wall and rotor at least as wide as the gap between the guide body and rotor, and the portion of said guide body opposite the guide Wall and the guide wall both being continuously curved in said predetermined direction, the curve of the portion of the guide body opposite the guide wall being tighter than that of the guide wall so that the discharge region has the form of a diffuser curved in said predetermined direction having a continuously curved center line extending over the length of the ditfuser, the guide means and rotor cooperating on rotation of the latter in said predetermined direction to set up a vortex of Rankine character having a core region eccentric of the rotor and extending into said gap between the guide body portion and the rotor to form a seal between said entry and discharge regions said vorteX having also a field region wherein fluid is guided from the entry region through the path of the rotating blades of the rotor to the interior space within the rotor and thence again through the path of the rotating blades of the rotor to the discharge region flow taking place through the rotor in planes transverse to the rotor axis and as seen in such planes being strongly curved about the vortex core, the curve of the flow through said rotor being continued in said discharge region whereby said dilfuser converts uneven velocity of flow of fluid entering said discharge region to an increase in pressure which is substantially uniform over the outlet of the diffuser.

References Cited UNITED STATES PATENTS 2,942,773 6/1960 Eck 230- 3,035,760 5/1962 Simmons 230-125 FOREIGN PATENTS 373,998 4/1907 France.

OTHER REFERENCES 1,052,625, March 1959, Germany printed application. 1,074,816, February 1960, Germany printed application.

DONLEY J. STOCKING, Primary Examiner. HENRY F. RADUAZO, MARK NEWMAN, Examiners. 

1. A MULTI-STAGE FLOW MACHINE COMPRISING A HOUSING DEFINING A INLET ADJACENT ONE END AND AN OUTLET ADJACENT THE OTHER, A ROTOR ASSEMBLY MOUNTED WITHIN SAID HOUSING FOR ROTATION ABOUT AN AXIS AND COMPRISING A PLURALITY OF CONSTITUENT ROTORS, ONE FOR EACH STAGE AND EACH HAVING LONGITUDINALLY DISPOSED BLADES ARRANGED IN A RING ABOUT THE AXIS TO DEFINE AN INTERIOR SPACE, WALL MEANS DIVIDING THE HOUSING INTO A PLURALITY OF COMPARTMETS ONE FOR EACH CONSTITUENT ROTOR, GUIDE MEANS DEFINING WITH THE ROTOR IN EACH COMPARTMENT AN ENTRY AND A DISCHARGE REGION, THE GUIDE MEANS IN EACH COMPARTMENT CO-OPERATING WITH THE ROTOR THEREIN ON ROTATION OF THE LATTER IN SAID PREDETERMINED DIRECTION TO SET UP A VORTEX OF RANKINE CHARACTER HAVING A CORE REGION ECCENTRIC OF THE ROTOR AXIS AND ADJACENT THE GUIDE BODY AND A FIELD REGION WHEREIN FLUID IS GUIDED FORM THE ENTRY REGION THROUGH THE PATH OF THE ROTATING BLADES OF THE ROTOR TO THE INTERIOR SPACE WITHIN THE ROTOR AND THENCE AGAIN THROUGH THE PATH OF THE ROTATING BLADES OF THE ROTOR TO THE DISCHARGE REGION FLOW TAKING PLACE THROUGH THE ROTOR IN PLANES TRANSVERSE TO THE ROTOR AXIS AND AS SEEN IN SUCH PLANES BEING STRONGLY CURVED ABOUT THE VORTEX CORE, SAID GUIDE MEANS ALSO DEFINING A DIFFUSER BETWEEN EACH PAIR OF ADJACENT COMPARTMENTS SAID DIFFUSER HAVING A CENTRE LINE WHICH IS CONTINUOUSLY CURVED IN THE SAME SENSE AS FLOW THROUGH THE ROTOR AND LEADING FLOW FROM THE ROTOR NEARER THE INLET TO THE ENTRY REGION OF THE ROTOR NEARER THE OUTLET THE ROTOR NEAREST THE INLET HAVING ITS ENTRY REGION COMMUNICATING THEREWITH AND THE ROTOR NEAREST THE OUTLET DISCHARGING THERETHROUGH. 